Spherical indicators for aircraft

Abstract

A spherical indicator for use on board an aircraft comprises one or more pointers supported by members which are mounted to rotate in front of a sphere of the indicator. The member which supports a pointer is mounted to rotate about an axis which passes through the center of the sphere.

What is claimed is: 
     
       1. A spherical indicator for the position of an aircraft, comprising a pointer, a member supporting the pointer which member is mounted to rotate whereby the pointer can move in front of a sphere in order to illustrate a variation between the position of the aircraft and a guide line, said member being mounted to rotate about an axis which passes through the centre of the sphere, said member comprising a ring centered on an axis of the sphere, and said ring being located substantially in a plane tangential to the sphere. 
     
     
       2. A spherical indicator as claimed in claim 1, in which said ring is mounted loosely in a cut-out defined by a plate attached to the spherical indicator. 
     
     
       3. A spherical indicator as claimed in claim 1, in which said ring bears laterally against rollers. 
     
     
       4. A spherical indicator as claimed in claim 1, in which the ring is set in rotation by a belt which travels under the action of a motor. 
     
     
       5. A spherical indicator as claimed in claim 4, in which the belt contacts the ring and means are provided for imparting tension to the belt, rollers being provided to serve as a lateral support for the ring under the action of this tension. 
     
     
       6. A spherical indicator as claimed in claim 1, which further comprises a motor, a transmission unit between this motor and said member in order that the motor sets the member in rotation, control means for producing an electrical signal representative of the position of the pointer, and a differential amplifier whereof the inputs respectively receive an electrical signal representative of the variation to be illustrated and a signal representative of the position of the pointer and whereof the output controls said motor, so that the motor is inoperative when the pointer is in the position representative of the value of the variation. 
     
     
       7. A spherical indicator as claimed in claim 6, in which the control means comprise a potentiometer whereof the slide is integral with said member and whereof the track extends over a circle whose centre is located on said axis. 
     
     
       8. A spherical indicator as claimed in claim 1, in which the member and a motor which drives the latter are both mounted on a plate attached on one side of the spherical indicator.